Single-Event Effects and Radiation Hardening in Digital Circuits

Abstract

Single-event effects (SEEs) are a group of phenomena manifesting for the most part, in integrated circuits (ICs). SEEs are disruptions in the operation of circuits, that are caused by ionizing radiation. The kind of ionizing radiation most commonly associated with SEEs is high energy particle radiation, such as very fast-moving alpha particles and other heavier ions. The highest particle fluxes in nature are encountered in space and high in the atmosphere. This is a cause of major concern for the reliability of modern systems operating in these conditions. Bit flips and data corruption are the most concerning outcomes of SEEs along with total system failures and damaged circuitry. There exists, however, a multitude of radiation hardening methods for ICs designed to combat SEEs and their consequences. This thesis presents a literary overview of SEEs and physics related to them as well as a look at common radiation hardening methods, all from the point of view of digital systems. Firstly, background physics and radiation environments relevant to this thesis are laid out. In the third chapter, common relevant SEE types are discussed: single-event upset (SEU), single-event functional interruption (SEFI), single-event transient (SET) and single-event latchup (SEL). Finally, relevant radiation hardening methods are presented. These are split into radiation hardening by process (RHBP) and radiation hardening by design (RHBD). It is concluded in this thesis that there are many ways to combat SEEs in ICs with different circuit designs and manufacturing processes. Other radiation hardening methods are more relevant than others and RHBD has become the preferred method to RHBP due to modifications to manufacturing processes being a costly endeavor. Space exploration has been a growing area of interest over recent years so more knowledge over the challenges of digital systems in this environment has become paramount.